Rocker arm construction

ABSTRACT

Disclosed is a unique configuration of a rocker arm per se wherein high stress areas thereof are strengthened and a trunion shaft is rotatively mounted on its push rod end and has a threaded push rod end insertion bore, a unique push rod construction per se wherein the upper end thereof is threaded, the combination of this rocker arm and the push rod wherein the upper end of the push rod is threaded into the insertion bore whereby the sudden, rapid, repeated and severe impact forces of the push rod end against the rocker arm are spread throughout the threaded connection and the rocker arm and are thus greatly diminished for each point of force contact between the push rod and the rocker arm, and further the stated combination mounted on an internal combustion engine.

BACKGROUND OF THE INVENTION

1. Field

This invention is in the field of internal combustion engines,particularly automotive engines having rocker arms and push rods andmore particularly concerns that structural portion of a rocker arm whichcontacts the upper end of a push rod, and further concerns the push rodconstruction, per se and the combination of an internal combustionengine employing the present rocker arm and push rod.

2. Prior Art

Heretofore, the receiving socket for the upper end of a push rod of atypical internal combustion engine rocker arm has been a concave surfacein which the rounded upper end of the push rod nests and which end canactually rotate about its longitudinal axis within the socket since thelower end of the push rod also nests in the concave top of a push rod(or valve) lifter. In these structures there is no actual mechanicallinkage connection of either end of the push rod to any other part ofthe valve opening and closing mechanism. As a result, and as aconsequence of the rapid, repeated impact force on the push rodreceiving socket on the rocker arm, particularly at rpm's such as 9,000or more, this socket is typically destroyed before its time as well asincurring premature breakage of the adjacent portions of the rocker arm.

Also inherent in prior rocker arm constructions, particularly whereinsolid (non-hydraulic) lifters are employed is the loose contact of thepush rod with the rocker arm especially in a cold engine. This loosenesscan cause the valves to open a lesser degree than optimum designedoperating conditions require.

SUMMARY OF THE INVENTION

The present invention comprises a unique configuration of a rocker armper se, intake or exhaust, of e.g., high strength and high performancemachined or cast steel or stainless, wherein high stress areas arestrengthened, a unique push rod per se, the combination of this rockerarm and the push rod, and this combination in use in an internalcombustion engine. In the aforesaid combination a rotative bearingconnection is provided between the upper end of the push rod and therocker arm whereby the sudden, rapid, repeated and severe impact forcesof the push rod end against the rocker arm are spread throughout a heavyduty bearing connection and are thus greatly diminished for each pointof force between the push rod and the rocker arm.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further understood from the drawings herein anddescription, wherein the structures in the figures are not drawn toscale or in proportion to each other, wherein certain structures arecross-sectional or broken away for clarity, wherein certain structuralportion are outline by jagged lines, and wherein:

FIG. 1 is a top down view of the present rocker arm with certainstructural portions broken away for clarity;

FIG. 2 is a bottom up view of the rocker arm of FIG. 1 also with certainstructural portions broken away for clarity;

FIG. 3 is an end view of the rocker arm of FIG. 2 taken in the directionof 3-3 in FIG. 2 without any shafts shown;

FIG. 4 is an end view of the rocker arm of FIG. 1 taken in the directionof 4-4 in FIG. 1 without any shafts shown;

FIG. 5 is a side view of the rocker arm body (without shafts) of FIG. 1taken in the direction of 5-5 therein;

FIG. 6 is a longitudinal cross sectional view of the rocker arm of FIG.1 with the upper portion of the present push rod mounted therein, astaken in the direction of 6-6 in FIG. 1;

FIG. 7 is a top down view of the push rod-to-trunion shaft connectionstructure of FIG. 6 taken in the direction of 7-7 therein;

FIG. 8 is an enlarged cross-sectional view of the drawn-up needle rollerbearing mounting for the end portion of the trunion shaft of FIG. 1 orthe pivot shaft of FIG. 2, taken in the direction of 8-8 therein;

FIG. 8A is a side view of a snap ring structure useful in securingshafts herein to the rocker arm body;

FIG. 9 is a side view of the trunion shaft of FIG. 1 showing the flatfor the push rod position setting or locking nut;

FIG. 10 is a front view of the rocker arm of FIG. 6 taken in thedirection of line 10-10 therein without the push rod and pivot shaftshown;

FIG. 11 is a schematic view of a typical rocker arm of the presentinvention with certain exemplary dimensions shown;

FIG. 12 is a side view of the present push rod structure with portionsbroken away for clarity;

FIG. 13 is a side view of a typical mechanical lifter engaging acamshaft and employing the present push rod and showing the oil pathstherethrough in arrowed line;

FIG. 14 is a mainly cross-sectional representation of portions of aninternal combustion engine with a lifter and the present push rod androcker arm combination mounted thereon wherein various engine structuresare not in proportion or to scale and are meant to illustrate commonfeatures of an internal combustion engine;

FIG. 15 is a view of a portion of a roller lifter, which portion can beused with solid (mechanical) or hydraulic lifters; and

FIG. 16 is a top down view of the cylinder head of FIG. 14 with thepresent combination of push rod and rocker arm mounted thereon.

In further explanation of the process or mechanical functioning thattakes place in an internal combustion engine having the present push rodand rocker arm combination, the present change that is taking place isin the area where the push rod meets the rocker arm pivoting point andin the harmonic's of the rocker arm design.

In an internal combustion engine of conventional design the push rod tip(upper end) has either a ball or cup design, either in the push rod orthe rocker arm. This design creates friction in the ball and cup areawhich is lubricated by oil coming through an oil passage through thepush rod and oiling the ball and cup.

The present design does not function with a ball and cup design andessentially eliminates rubbing friction in this area of contact betweenthe push rod and rocker arm in that it functions off of a fulcrum,rather than a ball and cup. The push rod and the adjuster (threaded pushrod end) are all one unit. The push rod screws into a trunion shaft thatserves as a fulcrum for the push rod and rocker arm in which theadjuster is locked in place with a locking nut. The trunion shaft ismounted into the rocker arm with caged needle roller bearings which areoiled by oil coming through the push rod and falling into a specialdesign reservoir made into the rocker arm. This structure oils thetrunion shaft and the main (mounting) shaft of the rocker arm.

The harmonic's of a standard roller rocker arm are such that the energytravels through the push rod and meets the rocker arm and makes a suddenchange in the direction of the energy transmission to the valve andvalve spring.

The present design as described more fully below with reference to FIG.6, allows the force energy to travel through the push rod and into therocker arm and then in a radius “r” to the valve and valve spring. Thiscreates a smoother transfer of energy from the push rod through therocker arm to the valve and valve spring. By way of this design theengine speed comes up more quickly in a shorter time cycle andessentially eliminates push rod and rocker arm damage.

DETAILED DESCRIPTION

The present invention will be understood further by reference to thedrawings and claims herein, wherein the invention is defined in one ofits broad embodiments as the combination of a rocker arm 10 and push rod12, wherein the rocker arm comprises a body 14 having a longitudinalaxis plane 15, a vertical axis plane 21, a valve stem contact endportion 16, a push rod connection end portion 18, and an intermediatesection 20 which is provided with a pivot shaft 22 adapted for pivotallymounting the rocker arm on an engine head. Any convenient structure ofthis pivot shaft for mounting the ends 31 and 33 of the rocker arm on aparticular head configuration can be employed, and FIG. 14 shows apreferred structure.

A trunion shaft 24 is rotatably mounted through bearing means 25 on endportion 18 and is adapted to be affixed in a set (but adjustable)position on the upper end 26 of the push rod 13 whereby pivoting of thearm 10 on the shaft 22 will cause the trunion shaft 24 to rotate andsubstantially maintain the axial posture 28 of the push rod. The plane15 passes through the centers of shaft 22 and 24, and the plane 21passes through the center of shaft 22 at a right angle to plane 15.

The upper end 26 of the push rod is threaded at 30, preferably machinethreads, wherein the shaft 24 is provided with a bore 32 having threads34 mating with threads 30 whereby the push rod can be screwed axiallythrough bore 32 to adjust a valve lift distance, and wherein a lock nut36 is threaded onto the upper end 26 and is adapted to tightly engage aflat 35 on shaft 24 and prevent rotation of the push rod within the bore32. A washer 29 is preferably employed between the nut and the shaft.

The body end portion 18 is provided with interior wall means 37 formingan opening 38 generally vertically through body portion 18 and thetrunion shaft is rotatably mounted generally laterally through saidopening to expose upper portions 11 and 13 of walls means 37 to therebyform an oil reservoir 41 around shaft portions 40 which receives oilpumped through first passage mean 42 in the push rod A second oilpassage means 44 is formed through body 14 and communicates with thereservoir 41 and the pivot shaft 22 for lubricating the same.

A roller 39 is rotatably mounted in bearing means 43 on a roller shaft45 fixed in end portion 16 of the body and is adapted to contact the end47 of a valve stem. A top portion of the body is formed with a cavity 46which can become filled with oil which is pumped up through the pushrod. A third oil passage means 48 is formed through the body andcommunicates with cavity 46 and the roller to lubricate the bearingmeans 43.

Each bearing means for mounting both the trunion shaft 24 and pivotshaft 22 preferably comprises a needle bearing such as generallydesignated 49 pressed into each end 50 and 52 of a shaft mounting bore29 or 54. The shaft 24 is formed with an enlarged diameter centersection 56 and reduced diameter end sections 58 and 60, wherein saidcenter section slidably engages wall means 37 to form said oil reservoir41. The junctions of the center section and end sections provide annularshoulders 62 and 64, wherein each cage 66 of the needle bearings bearsagainst one of said shoulders. The needle bearing cages 66 are pressfitted into bore 54 with the rollers 63 rollably engaging the endportions of shaft 24. An annular groove 68 is formed in each end section58 and 60 and a snap ring 70 is positioned in each groove whereby anexceedingly strong mounting of the trunion shaft on the body isafforded.

Referring to FIG. 6, an important aspect of the most preferredembodiment of the present invention is that at least about 60% andpreferably from about 70% to about 85% of the mass of the present rockerarm (without shaft 22, push rod 12 and nut 36) lies above axis plane 15of the body and provides greatly enhanced strength to the rocker arm aswell as a relatively large mass through which force energy is morereadily transmitted from the push rod to the valve stem. As seen furtherfrom FIG. 6, the configuration of the present rocker arm allows the pushrod force energy to travel through the body in an arc or radius from theaxis of pivot shaft 24 generally designated “r” as shown schematicallyby the dotted arrow lines in FIG. 6. Surface means 23 approximatelydefined by “r” preferably is substantially uniform, i.e., within about10% of a completely uniform radius throughout the 90° quadrant betweenthe longitudinal axis plane 15 and the vertical axis plane 21 of therocker arm body.

The present unique push rod 12 comprises an elongated body portion 51,preferably round in cross-section and integral with a lower end section53 having a rounded or similarly radiused end surface 55, and with anupper threaded end section 59. An oil passage 61 is provided completelythrough the rod in conventional manner. The ratio of the diameter “d” ofsaid body portion 51 to the diameters “d”, and “d₂” is preferably fromabout 1.2/1 to about 2.0/1 such that the body portion will not flex toany significant degree when under endwise pressure. Otherwise suchflexing would alter the designed degree of value opening. In theembodiment shown, the total length of the push rod is approximately 11.5in. and the length of body portion 57 is approximately 8.0 in.

In a comprehensive embodiment of the present invention, the presentrocker arm and push rod combination is mounted on an internal combustionengine such as a typical V6, V8, or in line cylinder arrangement of anyconventional design and number of cylinders. A typical such engine isthe Chevrolet V8 engines shown in The Haynes Chevrolet Engine OverhaulManual, Library of Congress Catalog Card Number 91-71154, thedisclosures of which are hereby incorporated herein by reference intheir entireties.

A schematic exemplary showing of portions of an internal combustionengine with the present rocker arm and push rod combination thereon isgiven in FIGS. 14 and 16 wherein, in a simplified form, the enginecomprises an engine block 17, a cylinder head 72 mounted thereon, anexhaust (or intake) valve 73 mounted in said head, a cylinder 74 formedin said block, a piston 75 mounted in said cylinder and connected by aconnecting rod 80 to a crankshaft 76 mounted in said block, a camshaft77 with its lobes 84 mounted in said block and engaging a lifter 78mounted in said block, and a spark plug 79 mounted through said head andcommunicating with said cylinder 74.

Each pivot shaft 22 for the present rocker arms is bolted by bolts 82 toa rocker arm stand generally designated 81 which is bolted by bolts 83to head 72. Each lifter 78 is in communication with the pressurizedlubrication lines 85 of the engine, and the top cap or push rod nest 86thereof is provided with an oil passage 87 which feeds oil underpressure into oil passage 61 in the push rod.

This invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications will be effected within the spirit and scope of theinvention.

1. The combination of a rocker arm and a push rod for use in an internalcombustion engine, wherein said rocker arm comprises a body having alongitudinal axis plane, a valve stem contact end portion, a push rodconnection end portion, and an intermediate portion which is providedwith pivot means adapted for pivotally mounting the rocker arm on anengine head, wherein a trunion shaft is rotatably mounted in bearingmeans on said push rod connection end portion and is affixed in anadjustable set position on an upper end of said push rod, wherebypivoting of said arm on an engine head will cause said trunion shaft torotate and substantially maintain an operative axial posture of the pushrod, and wherein said push rod is externally threaded at its upper end,wherein said trunion shaft is provided with a bore having internalthreads mating with the push rod threads whereby said push rod can bescrewed axially through said bore to adjust a valve lift distance, andwherein a nut is threaded onto said upper end and adapted to tightlyengage said trunion shaft and prevent untimely rotation of said push rodwithin said bore.
 2. The combination of claim 1 wherein said push rodconnection end portion connection end portion is provided with interiorwall means forming an opening generally vertically through saidconnection end portion and wherein said trunion shaft is rotatablymounted generally laterally through said opening whereby upper portionsof said trunion shaft and said nut are exposed, wherein central portionsof said trunion shaft slidably engage portions of said wall means tothereby form an oil reservoir in which said upper portions lie, andwherein said reservoir is adapted to receive oil pumped up through firstoil passage means in said push rod whereby the contacting surfaces ofsaid trunion shaft and said body are substantially continually floodedwith lubricant during engine operation.
 3. The combination of claim 2wherein second oil passage means is formed through said body andcommunicates with said reservoir and said pivot means for lubricatingsaid pivot means.
 4. The combination of claim 3 wherein a roller isrotatably mounted on a roller shaft fixed in said contact end portion ofsaid body and is adapted to contact the end of a valve stem, wherein atop portion of said body is formed with a cavity which becomes filledwith oil which is pumped up through said push rod, and wherein third oilpassage means is formed through said body and communicates with saidcavity and said roller and roller shaft to provide substantiallycontinuous lubrication therefor during engine operation.
 5. Thecombination of claim 1 wherein said bearing means comprises a pair ofneedle bearings, each cage thereof being pressed into an end of amounting bore for said trunion shaft in said body.
 6. The combination ofclaim 5 wherein said trunion shaft is formed with an enlarged diametercenter section and reduced diameter end sections, wherein said centersection slidably engages said wall means to form said oil reservoir,wherein the junctions of said center section and end sections provideannular shoulders, wherein the cage of each needle bearing bears againsta said shoulder, wherein an annular groove is formed in each said endsection, and wherein a snap ring is positioned in each said groove andis adapted to bear against an adjacent surface of said body whereby anexceedingly strong and stable mounting of said trunion shaft on saidbody is afforded.
 7. The combination of claim 1 wherein said body isconfigured to provide a substantially uniformly radiused surface meansextending in a substantially uniform arc between a longitudinal axisplane and a vertical axis plane of said body, whereby an additionalrelatively large mass is afforded to said body above said longitudinalaxis plane, and whereby push rod force energy can be transmitted throughsaid body, generally along said arc.
 8. In an internal combustion enginehaving an engine block with at least one cylinder formed therein, acylinder head mounted on said block over the top of said cylinder, valvemeans mounted in said cylinder head and communicating with saidcylinder, a piston mounted in said cylinder for reciprocation therein,and cam shaft means mounted in said block and engaging valve liftermeans mounted in said block, the combination of a rocker arm and a pushrod for said engine, said rocker arm being mounted on said head and saidpush rod being pivotally affixed to said rocker arm, wherein said rockerarm comprises a body having a longitudinal axis plane and a verticalaxis plane and further having a valve stem contact end portion, a pushrod connection end portion, and an intermediate portion which isprovided with a pivot shaft for pivotally mounting the rocker arm onsaid head, wherein each end section of a trunion shaft is rotatablymounted in bearing means on said push rod connection end portion of saidbody and is affixed in an adjustable set position on the upper end ofsaid push rod whereby pivoting of said rocker arm on said pivot shaftwill cause the trunion shaft to rotate and substantially maintain theaxial operative posture of the push rod during engine operation, andwherein the upper end of said push rod is externally threaded, whereinsaid trunion shaft is provided with a bore having internal threadsmating with said threads on said push rod whereby said push rod can bescrewed axially through said bore to adjust to a specified valve liftdistance, and wherein a nut is threaded onto said upper end of said pushrod and adapted to tightly engage said trunion shaft and preventrotation of said push rod within said bore.
 9. The engine of claim 8wherein said push rod connection end portion is provided with interiorwall means forming an opening generally vertically through saidconnection end portion and wherein said trunion shaft is rotatablymounted in said connection end portion generally laterally through saidopening to expose upper portions of said trunion shaft and said nut, andwherein said trunion shaft slidably engages portions of said wall meansto thereby form an oil reservoir around said upper portions whichthereby receive oil pumped up through first oil passage means generallyaxially formed through said push rod.
 10. The engine of claim 9 whereinsecond oil passage means is formed through said body and communicateswith said reservoir and said pivot shaft.
 11. The engine of claim 9wherein a roller is rotatably mounted by bearing means on a roller shaftfixed in said contact end portion and is adapted to contact the end of avalve stem, wherein a top portion of said body is formed with a cavitywhich becomes filled with oil which is pumped through said push rodduring engine operation, and wherein third oil passage means is formedthrough said body and communicates with said cavity and said roller tolubricate said bearing means.
 12. The engine of claim 9 wherein eachsaid bearing means comprises a needle bearing, the cage of which ispressed into an end and of a shaft mounting bore formed laterallythrough said body.
 13. The engine of claim 12 wherein said trunion shaftis formed with an enlarged diameter center section and reduced diameterend sections, wherein said center section is slidably engaging said wallmeans to form said oil reservoir, wherein the junctions of said centersection and end sections provide annular shoulders, wherein each cage ofthe needle bearings bears against a said shoulder, wherein an annulargroove is formed in each end section, and wherein a snap ring ispositioned in each said groove whereby an exceedingly strong mounting ofsaid trunion shaft on said body is afforded.
 14. The engine of claim 8wherein said body is configured to provide a substantially uniformlyradiused surface means on said connection end portion and extending in asubstantially uniform arc between a longitudinal axis plane and avertical axis plane of said body, whereby an additional relatively largemass is afforded to said body above said longitudinal axis plane, andwhereby push rod force energy can be transmitted through said bodygenerally along said arc.